1,721,024 research outputs found
Determinants of Paternity in Rhesus Macaques: Influence of the Timing of Mate Guarding with the Fertile Phase
No full textDo males time their mate-guarding effort with the fertile phase in order to secure fertilisation in Cayo Santiago rhesus macaques?
No full textIn contrast to most mammalian species, female sexual activity is not limited to the fertile phase of the ovarian cycle in anthropoid primates, which has long been proposed to conceal the timing of ovulation to males. It is now generally believed that females are still most attractive during the fertile phase, leading to high-ranking males successfully mate-guarding them specifically during this period. While studies conducted in species exhibiting exaggerated sexual swellings (probabilistic signal of the fertile phase) have generally supported this hypothesis, mixed support comes from others. Here, we investigated whether high-ranking males timed mate-guarding effort towards female fertile phases in rhesus macaques (Macaca mulatto). In this species, adult females do not exhibit sexual swellings, but undergo facial skin colour variation, an alternative oestrogen-dependent graded-signal of female reproductive status. We collected behavioural, hormonal and genetic paternity data during two mating seasons for one group of the free-ranging population of Cayo Santiago. Our results show that mate-guarding by top-ranking males did not completely cover the entire female fertile phase and that this tactic accounted for only 30-40% of all fertilisations observed. Males tended to prolong mate-guarding into the luteal phase (null probability of fertilisation), which mirrors the pattern of male attraction to female facial colour reported in an earlier study. These findings suggest that males may have limited knowledge regarding the exact timing of females' fertile phase in rhesus macaques, which presumably allows females to gain more control over reproduction relative to other anthropoid primate species. (C) 2012 Elsevier Inc. All rights reserved
Determinants of Paternity in Rhesus Macaques: Influence of the Timing of Mate Guarding with the Fertile Phase
No full textTemporal dynamics and fitness consequences of coalition formation in male primates
No full textCoalition formation is one of the most striking forms of cooperation found in animals. Yet, there is substantial variation between taxa regarding the mechanisms by which coalitions can result in fitness consequences. Here, we investigate the influence of coalitions on dominance rank trajectories and subsequently on reproductive success in wild male crested macaques (Macaca nigra) at Tangkoko Nature Reserve (Sulawesi, Indonesia). We observed 128 coalition events involving 28 males and tested how a variety of coalition properties and factors related to the social environment influenced future male rank. We further used genetic paternity analysis of 19 infants conceived during the study to assess male reproductive success. Our results show that males participating in coalitions achieved higher-than-expected future ranks, while coalition targets had lower-than-expected future ranks. Additionally, all-up coalitions had stronger effects on rank than all-down and bridging coalitions, and these were modulated by the relative strength of coalition partners versus targets. Finally, higher ranking males were more likely to sire infants than lower ranking males. These results provide important insights regarding the mechanisms underlying coalition formation and support the idea that one major path by which coalitions can affect fitness is through influencing male dominance trajectories
Growing into the self: The development of personality in rhesus macaques
No full textAlthough personality has been widely studied among animal species, only a few studies have investigated the long-term development of personality during early ontogeny. In fact, no study of nonhuman primates has consistently mapped personality development from birth to adulthood. Our study aimed at closing this gap by examining the development of personality among free-ranging rhesus macaques, Macaca mulatta, using longitudinal behavioural data of 24 subjects (3758 h) collected from birth to 7 years of age on the island of Cayo Santiago, Puerto Rico, U.S.A. In our analyses we combined different frameworks of animal personality research to discuss behavioural differences in terms of latent personality models, behavioural syndromes and behavioural characters. The results showed that a core model of rhesus macaque personality, comprising three latent factors (Fearfulness, Aggression, Sociability), can already be established over the course of the first 7 years of life. However, only Fearfulness emerged consistently throughout development. While the factor of Sociability diffused during maturation, Aggression stabilized towards adulthood after having inconsistent loadings during infancy. When assessing correlations among behaviours separately on the within- and between-individual level, again only Fearfulness showed significant results averaged over the entire study period and can therefore be classified as behavioural syndrome or behavioural character. We discuss differences in correlations, interactions between sex and age and the effect of maternal rank as potential source of differences in stability of latent traits. Furthermore, we assessed plasticity of behaviour with regard to first maternity in females and natal dispersal of males. While the latter was accompanied by an increase of fearful behaviour and decrease of physical aggression, first maternity was marked by a mixed pattern of changes. Overall, our results suggest that rhesus macaques are not born into their personality, but grow into it. (C) 2016 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved
Female fertile phase synchrony, and male mating and reproductive skew, in the crested macaque
No full textAbstract
High social status is the primary determinant of reproductive success among group-living male mammals. Primates living in multimale–multifemale groups show the greatest variation in the strength of this link, with marked variation in reproductive skew by male dominance among species, dependent on the degree of female fertile phase synchrony, and the number of competing males. Here, we present data on two groups of wild crested macaques (
Macaca nigra
), living in the Tangkoko Reserve, Sulawesi, Indonesia. We investigated male monopolization of fertile females in 31 cycles of 19 females, and genetic paternity of 14 offspring conceived during the study period. We show that female fertile phase synchrony was low, that females had few mating partners in their fertile phase, and that dominant males monopolized a high proportion of consortships and matings, resulting in marked and steep mating and reproductive skew. We conclude that female cycle asynchrony provides the opportunity for strong direct male–male competition in crested macaques, resulting in monopolization of females by dominant males, consistent with their marked sexual dimorphism. Our study provides a test of the underlying factors that determine the relative occurrence and strength of different mechanisms of sexual selection, and the phenotypes that evolve as a result.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Projekt DEA
Combined perceptual and chemical analyses show no compelling evidence for ovulatory cycle shifts in women’s axillary odour
No full textAlthough men’s attraction to women’s body odour has been suggested to vary over the ovulatory cycle, peaking around the fertile window, we still lack methodologically robust evidence corroborating this effect. Further, the chemical underpinnings of male preference for the odour of ovulating women remain unknown. Here, we combined perceptual and chemical analyses to investigate the axillary odour of naturally cycling women over 10 days, covering the gradual change in fertility across the ovulatory cycle with a focus on fertile days. The fertile state was confirmed by urinary ovulation tests as well as salivary oestradiol and progesterone levels. Men rated the scent of unfamiliar women, resembling a first encounter. We used multivariate analyses to relate variation in both odour ratings and chemical composition to female conception probability, temporal distance to ovulation and ovarian hormone levels. Our results provide no evidence that males prefer the odour of fertile women. Furthermore, the volatile analysis indicated no link between axillary odour composition and current fertility status. Together, our results showed no convincing support for a chemical fertility cue in women’s axillary odour, questioning the presence of olfactory fertility information that is recognizable during first encounters in modern humans.The Leakey Foundation 100005966Saxonian graduate scholarshipLeipzig University 501100008678European Fund for Regional Structure Development, EFR
Highly polymorphic microsatellite markers for the assessment of male reproductive skew and genetic variation in Critically Endangered crested macaques (Macaca nigra)
Full text linkGenetic analyses based on non-invasively collected samples have become an important tool for evolutionary biology and conservation. Crested macaques (Macaca nigra), endemic to Sulawesi, Indonesia, are important for our understanding of primate evolution as Sulawesi macaques represent an exceptional example of primate adaptive radiation. Crested macaques are also Critically Endangered. However, to date we know very little about their genetics. The aim of our study was to find and validate microsatellite markers useful for evolutionary, conservation and other genetic studies on wild crested macaques. Using faecal samples of 176 wild macaques living in the Tangkoko Reserve, Sulawesi, we identified 12 polymorphic microsatellite loci through cross-species PCR amplification with later modification of some of these primers. We tested their suitability by investigating and exploring patterns of paternity, observed heterozygosity and evidence for inbreeding. We assigned paternity to 63 of 65 infants with high confidence. Among cases with solved paternity, we found no evidence of extra-group paternity and natal breeding. We found a relatively steep male reproductive skew B index of 0.330±0.267; mean±SD) and mean alpha paternity of 65% per year with large variation across groups and years (29-100%). Finally, we detected an excess in observed heterozygosity and no evidence of inbreeding across our three study groups, with an observed heterozygosity of 0.766±0.059 and expected heterozygosity of 0.708±0.059, and an inbreeding coefficient of -0.082±0.035. Our results indicate that the selected markers are useful for genetic studies on wild crested macaques, and possible also other Sulawesi and closely related macaques. They further suggest that the Tangkoko population of crested macaques is still genetically variable despite its small size, isolation and the species’ reproductive patterns. This gives us hope that other endangered primate species living in small, isolated populations may also retain a healthy gene pool, at least in the short term
Do Wild, Male, Crested Macaques (Macaca nigra) Respond to the Screams of Infants Involved in Agonistic Interactions?
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